The present invention, in some embodiments thereof, relates to systems and methods for displaying stereoscopic image pairs viewable by a viewer without need of eyeglasses. Stereoscopic viewing without need of special eyeglasses is referred to as “autostereoscopy” herein.
Two well-known technologies, known as “lenticular” display systems and “parallax barrier” display systems, produce autostereoscopy by displaying left-image pixels (i.e. pixels intended for viewing by a left eye) on first stripes of a displayed image (usually, but not necessarily, vertical stripes) and reproducing right-image pixels (i.e. pixels intended for viewing by a right eye) on second stripes of that displayed image. In both technologies first and second stripes alternate with each other across the displayed image. Additional stripes from additional image views are also interleaved in some cases. In parallax barrier systems opaque portions of a barrier appropriately distanced from the display prevent the viewer's left eye from seeing the right-image pixels and prevent his right eye from seeing the left-image pixels. In lenticular systems, lenticles (micro-lenses) accomplish the same purpose by directing a viewer's left eye view toward left image pixels and preventing his left eye from viewing of right-image pixels, and directing his right eye's view towards right-image pixels and preventing it from viewing left-image pixels.
Such autostereoscopic systems may be contrasted with stereoscopic display technologies which do depend on use of eyeglasses. Some of these, called image-sequential systems, are designed to produce, in rapid sequence, a full-resolution left image (i.e. an image intended for viewing by a viewer's left eye), and then subsequently a full-resolution right image intended for viewing by the viewer's right eye. In some systems, “shutter glasses”, eyeglasses with small LCD eye windows which switch rapidly between being transparent and being opaque, are used to block the left eye when the right image is being displayed and block the right eye when the left image is being displayed. In other systems, where what are called “passive” polarizing glasses are used, left images are displayed polarized in a first orientation N°, and right images are display polarized in a second orientation, typically orthogonal to the first orientation, i.e. (N+90)°. As with the shutter-glass systems, alternation of images repeats rapidly and continuously, with left images alternating with right images many times a second. The viewer uses passive polarizing eyeglasses, so that his left eye has a polarizing filter in front of it in the first orientation, and his right eye has a polarizing filter in front of it in the second orientation. Through the filters, the left eye sees only the left images and the right eye sees only the right images.
PCT application WO97/026577 by Kleinberger et al. (referred to in the following as “PCTA”,) teaches inter alia a system whereby at a given time, one of a pair of stereoscopic images is displayed on all or part of a display in a format wherein first stripes reproducing pixels of that image are displayed in a first polarization orientation and second stripes reproducing pixels of that same image are simultaneously displayed in a second polarization orientation. A selective light-blocking layer interposed between display and viewer and comprising striped portions blocking light in the first orientation alternating with striped portions blocking light in the second orientation can be used to display light of the selected image (one image of a stereoscopic pair of images) to one viewer eye while preventing it being seen by the viewer's other eye. PCTA teaches use of this structure to provide full-resolution autostereoscopic viewing.
PCTA presents various other features and methods for stereoscopic and autostereoscopic system which aid in understanding some of the embodiments presented herein. The reader is referred in particular to discussions of movement permissiveness of autostereoscopic systems presented therein, and to discussions of configurations combining color filters to achieve autostereoscopy.
PCT Application WO01/18589 by Kleinberger et al. (referred to in the following as “PCTB”), and also U.S. Pat. No. 5,629,798 to Gaudreau, teach inter alia a full resolution display system in which left and right images are displayed simultaneously on all pixels of a display, each physical display pixel emitting light polarized in a first orientation and corresponding in intensity to a left image pixel at that position, and also simultaneously emitting light polarized in a second orientation orthogonal to the first, and corresponding in intensity to a right-eye image pixel at that position. A display screen of this design is referred to in this document as a “G Screen”. Kleinberger et al and Gaudreau teach use of eyeglasses having polarizing filters in front of each eye to transmit only left image light to the left eye and only right image light to the right eye, resulting in stereoscopic viewing.
PCTB also teaches organizing the image output of a G Screen in such a way that first sections alternate with second sections across the screen (a section being, for example, a vertical column of pixels one or several pixels wide), such that in first sections the left image is polarized in a first orientation and the right image in a second orientation, and in second sections the left image is polarized in the second orientation and the right image in the first orientation. PCTB shows how this display light can be viewed through a light-blocking layer implemented as a formatted polarizing filter near the display and having striped polarizing filters in alternating orientations, to enable full-resolution autostereoscopic viewing of both images simultaneously.
Contents of the above-referenced documents are hereby incorporated herein by reference.